1. Field of the Invention.
The invention relates to a coolable plunger piston for internal combustion engines.
2. The Prior Art.
This type of piston is known, for example, in the art based on U.S. Pat. No. 4,180,027. The aforementioned piston is cooled in the area of the piston head, both in the outer annulus, as well as in the radial, central internal area. Cooling oil is injected from the crankcase into the outer annulus in the upper portion of the piston. By means of liquid collection traps located at the upper end of the piston shaft, the cooling oil is able to penetrate the area inside the inner annular side support.
GB-A 2,148,451 discloses a similar piston. Here, too, the cooling oil intended for the area inside the inner annular side support can only be delivered via an external closed cooling conduit. Cooling oil which has been injected into the outer cooling conduit reaches, respectively, the center of the piston head via at least one radial aperture in the inner annular side support, by means of the mass forces operative during the oscillating movement of the piston on the cooling oil present in the cooling conduit. Direct spurting from the crankcase is impossible during the process, with the result that only cooling oil already previously warmed is able to access the center of the piston head.